Antiferromagnetic coupling and enhanced magnetization in all-ferromagnetic superlattices

The structural and magnetic properties of a series of superlattices consisting of two ferromagnetic metals La0.7Sr0.3MnO3 (LSMO) and SrRuO3 (SRO) grown on (001) oriented SrTiO3 are studied. Superlattices with a fixed LSMO layer thickness of 20 unit cells and varying SRO layer thickness show a sudden drop in magnetization on cooling through a temperature where both LSMO and SRO layers are ferromagnetic. This behavior suggests an antiferromagnetic coupling between the layers. In addition, the samples having thinner SRO layers (n < 6) exhibit enhanced saturation magnetization at 10 K. These observations are attributed to the possible modification in the stereochemistry of the Ru and Mn ions in the interfacial region.(c) 2006 American Institute of Physics.